Anthony's Lifting Messenger

The following is a discussion and plan for a messenger for ''lifting''
parafauna, candy, and other 'heavy' loads up a kite line.

Just for those wanting to know what a messenger is...

Kite Messenger or Ferry(n): A device which is pushed or pulled
up a kite line, usally by use of sails or parachute. When it hits a 'stop'
previously attached to the kite line at an appropriate height, a set of rods
are pushed which releases the sails and drops the 'load' carried by the
messenger. The messenger, with the sails now folded or parachute droped with
the 'load', then slides back down the kite line, where a new load can be
attached.

The messenger detailed by this plan will actually lift goods up
vertical lines! I did this as an experiment fully loaded. The design also
requires no adjustments are is typical of many messenger, or produce a lot a
wind drag. These factors were the is the goal of this plan, and in this
respect has been a total success.

I had decided to get into parafauna, and had even found the perfect
parachutist for the job, a small koala named Tuffy,
a few months before. The problem was that I did not want to pull the
kite down each time I wanted to drop my 'friend' or some candy, as I
would with a ''pull-line'' or timer line dropper device.

The only other solution other than a messenger is a manual pulley system,
such as Art & FlyWork's
Pully Dropper. But this seemed to me to be prone to problems,
particularly in unsteady and turbulent winds, and still requires a good
deal of work. Ok so I'm lazy, what else is new!

As such a messenger was the only real solution I saw as acceptable.

I have built messengers before, for example my Mintie Messenger is still a big hit with kids on the field. It is however
limited in the weight it can carry, such as a small number of minties,
ribbons, paper planes, etc. It also does not like the steep slope of most
good kites preferring the 30 degree slope of UFO kites. And finally the wind
needs to be really blowing really strongly, right down to ground level, for it
to work well.

The mintie messenger and all the other messenger plans I have seen used
basically square framed sails and as such were basically reasonably
heavy framed, relying on the wind to 'drag' it up the kiteline. I
thought this was most unreasonable considering that the users were
basically kite flyers, who I thought would have more sense. The more
I thought about it the less reasonable it became that messengers should
rely solely on drag to lift the load.

Then while surfing the net I came across a short mpeg of a teddy bear
drop, which showed a small bear being lifted up a near vertical
kiteline. The mpeg movie, now offline, showed a small and very oddly
shaped winged messenger carrying the bear up the kiteline. After some
discussion it was found the wind was quite strong and the messenger has
two adjustable release lines to set the sail angle.

More discussion followed from this on the rec.kites newsgroup during
June 1997, but with no real final result. Typical of a newsgroup.

Well I thought long and hard and theorized that a 'kite like' sail must
surely provide more lift than drag in a messenger. Finally I got round
to building a messenger to experiment with and try out ideas. The
following plan is the result.

Hint and Tip Ground winds are essential for launching messengers
however I have found that if the wind is not too high up, you can pull the
kite line down, a short distance down-wind from the tether point, moving the
messenger along the line to this point. When you release the kite line the
kite lifts the kite line, and the messenger into the wind. It should then be
out of the low ground wind and continue its journey up the kite line as
normal, then return to the tether point for re-loading.

The goal is to build a 'lifting messenger'' and that is achieved though
the sails of the messenger. The body of the messenger is not as
important as the shape and style of this has become reasonably standard.
I did however make a few small changes to the messenger particularly
with regard to the sail hinges. More about that latter.

The messenger body is basically a variation on a originally plan published by
Thomas Dorf Nielsen. The original plan is offline, but a mirror of the plan
is available from Kite Ferry. This plan was one of the first to appear and became
a standard plan in ferry messengers.

The plan uses carbon fiber (or other) rigid tubing to form the main body of
the messenger, through which 3mm fiberglass rods are inserted to provide the
release mechanism. The body of the messenger should be about the same length
or width (the longer) of the sail. The sail, when attached, will be
positioned around the forward 1/3 mark of the messenger body while the load
should be somewhere in the rear 1/3 section of the body. This is not
critical and can be adjusted as required for proper working.

You are free to use other components for the body, Aluminum/plastic tubing,
dowel rods, whatever. Weight is NOT critical, and can be compensated with a
larger sail.

The other parts of the messenger is attached using clear vinyl plastic
tubing of various sizes from the local hardware shops. No glue required.
The use of plastic tubing in the messenger makes it very easy to assemble
and disassemble the messenger, which in turn allows you to quickly try out
new ideas. I often create a few different sails, with my sail hinge (see
below) built in. On the fly day, I can then quickly and simply dis-assemble
the messenger, and re-assemble with a different sail to test out, ON THE
KITE FIELD. As such is this messenger design is perfect for general
experimentation.

The plastic tubing I have also found can take a huge amount of
punishment, especially in the sudden stop as the messenger returns
at break neck speeds down a near vertical kite line. The tubing just
absorbs the impact without breaking.

Having said that, I used "Dorf's Ferry: as the basic style of
construction, the following diagram details the new design developed from
Dorf's version. I have also gone into more detail than the original plan,
which should help with your own construction.

First thing to note is that I bound a group of carbon fiber tubes (each 3cm
long) together to provide the support of the load and release rod. I did
this for two reasons.

First by binding the rod supporting the load to the messenger body I
can ensure that the release rod always closes properly into the second
set of support tubes. In Dorf's Ferry the plastic load support tubes has
a tendency to twist requiring three or more hands to get things straighten
out when loading the messenger.

Secondly the support tubing used in Dorf's ferry had a tendency to hook
the parafauna or candy sack release, thus preventing the drop of the load.
Not a good idea with a group of kids waiting patiently (err...
impatiently) down wind for the prize. :-(

By binding the load support strongly like this means a stronger and more
secure connection to messenger body. Unfortunately it means that this part is
permanent and the sails can only be removed buy slinding the hinge off the
front of the messenger body.

ALSO NOTE: In my experimental messenger I found that when loaded, with the
hook far too close to the lower end of the messenger (as shown in the diagram
above) caused the front of the messager to lifting from the kite line. So in
the new one I extended the release rod to move the load away from the line
line support at the lower end of the messenger body. That is I moved the
release point position further along the body of the messenger.

Kite Line Attachment

The Line support of Dorf's Ferry has also been modified. Instead of
using a brass ring with a cut in it, I have carefully bent thick coat
hanger wire for the connection of the messenger to the kite line. This
makes it very easy to attach and detach the messenger from the kite line
without having to fiddle with the spilt rings. Similar wire arrangements
can be used for release line hooks for parafauna, or candy sacks.

I am still not happy with the 'slipperyness' of the coat hanger wire,
especially as I have found it gets a thin layer of rust after exposure
to salt sea spray and being put away for a period of time.

I would love to use graphite rings used in fishing rod rings. These rings
are ultra smooth and slippery, unfortunately this same bonus means that
these rings can not easily have a notch cut into them allowing a line to be
inserted. The fishing rod rings to hold the graphite rings are also quite
complex and can't accept a kite line in the middle without weakening them
considerably. These items are only designed to be threaded by the end of a
fishing or kite line, and not for attaching the messenger in the middle of the
line (once the kite is flying) which is a important feature of the kite line
attachments I am using.

UPDATE: A better alturnative is to use Stainless Steel Cotter Pins I found in
a marine shop. A little extra bending in a bench vice and you have a very good
and slippery, rust proof, line attachment.

UPDATE: 10 years later and I am still using those same cotter pins.
They are just great, and no complicated clips, wheels, line jams, and they
never rust.

Messenger Stops on Kite Line.

Not only does a 'messenger' need to be attached to the kite line, but also two
'stops', need to be added. An upper 'fixed' stop that the messenger will hit
and thus cause it to release its load. And a lower 'brake' stop.
These should be attached at appropriate moments while the kite is being
launched. The upper stop should be at leasy a few meters (yards) from the
kites bridle point, as you do not want to have the messenger getting tangled
in the kites bridle lines.
Also if the messenger gets too close to thge kite it can cause weight and wind
disturbances to upset the kite, and that is not good either. Keep them apart.
The upper 'stop' should not 'slip' along the kite line, and as such the line
should loop back on itself, as part of the attachment, so as to prevent it
slipping. Remeber that line also can have a lot of pull so make sure the
stop is strong enough.
I find a cork that is 'ladder knotted' onto the kite line is good enough
without being too fancy, or costly if 'lost'. The ladder knot ensures the
cork cannot slide, and does not fall off if the kite line becomes loose on the
ground.
UPDATE: Peter en Marleen Simons showed on his messager web pages
a much better stop, providing a good surface for the messenger to 'hit'.
Note however that if used as showm, the 'stop' can slip along the kite line.
A better attachment to the kite line is recommended.
In contrast the lower stop should be able to slip along the kite line to some
extent. This lets the fast decending messager slow down to a stop, without
suddenly jerking the line or hitting whatever it is you have tied your kite
line to.
For this a cork with a slit cut into it works well. The cork will slide down
the line when the returning messenger hits it, slowing it to a stop. Afterward
you can slide it back into position for the return from the next run.
Being loose, also allows you to move the lower stop qickly, when you need to
let kite line in or out, which can happen on days when the wind is light,
changes direction, or otherwise varies.

The final and MOST IMPORTANT change to Dorf's Ferry, is that I have used two
short segments of carbon fiber tubing to hinge the sails 'double spine' (see
below) to the messenger body. The use of a double spine is one of the
inovations of this experimental messenger. By doing this I find I have
absolutely no need of the elastic retraction line used in Dorf's Ferry. As
the sails are freely hinged, the wind will easily fold the sails up and away,
allowing the messenger to return (unless drag from sail flap becomes a
problem on a low angle line).

The hinge is created by punching holes into plastic tubing at right angles
(or other angles for further experimentation) to each other. This can NOT be
done with a knife. I myself use a cheap leather punch with various size
holes to select from. Alturnatively you could sharpen the edges a brass or
aluminium tube and use a drill to cut the holes in the tubing. The holes
should be quite a bit smaller than the carbon fiber tube to be inserted into
them to ensure a tight fit.

The hinge is then built into and becomes part of the sail. When you are
ready to you can then slide the center plastic tubing into the messenger
body, position it and slide extra plastic tubing around it to ensure it does
not move. This can be done on the flying field and different types of sails
(in size or shape) can be swapped as required for experiments and wind
conditions. Each sail with its own hinge.

UPDATE In one location I flew in, the turbulence due to a nearby
building played havoc with the sails. Because of this one side of the sail
sometimes falls down against the poor parafauna load, where it stayed. The
messager still rose but very slowly, with a lean to one side.

As such I now recommend a loose line from the back of the sail to the top
line support piller, to prevent any chance of the sails falling down from
bad wind turbulance.

NOTE this line is NOT normally nessary and in a clear field with good winds
near the ground, no problem requiring the line develops. It also does NOT need
to be elastic (such as the retact lines used in dorfs messager) and does not
need to be tight, just present to stop ''sail flop'' due to turbulence.

UPDATE: Later I replaced the vinal platic joining the two carbon
fiber tube hinges with a more ridgid plastic tube found in some unknown toy.
The more ridge tubing holds the sail spine more perpendicular to the
messenger body and seems to work better than the more flexiable vinal
tubing. It also does not wear out due to the twisting of the sail spine
relative to the messenger body as the previous vinal tubing did.

It is the sails of this messenger which is heart of the messenger.
And it is here that I am doing my experiments.

There are lots of different sails that can be used for a messenger.
But most if not all seem to only provide a drag surface to allow
the wind to push the messenger up the kite line. Indeed the simplest of
messengers use the parachute of the parafauna, solider or whatever
to provide the drag.

The problem with this is that first of all the kite line can not be very
steep, otherwise the messenger will not actually climb the kite line, just
drag the kite down. Secondly the messenger sail does not provide very much
lift, as such all the lift will have to be provided by the kite itself.

You must have then a strong pulling kite which is able to lift the
messenger and load. And as the kite line must be at a low angle
only the lines tension will lift the messenger. Which means the kite
must not only have to be able to lift the messenger and weight,
but it must pull the line extemely tightly too!.

Some of the newer messagers have sail angle adjustments. I find these
tedious and difficult to get right. By using kite sails, the sail themselves
can adjust the sail angle automatically. This is due to the sails I am using
extending ABOVE the line line and messager body itself. No more angle
adjustments! (See ridge tubing for hinge note above)

For my first lifting sail experiment I decided to go back to basics by
replacing the fully framed sail used in Dorf's Ferry, and in my own
Mintie Messenger, with a diamond kite sail. This however is not so
simple. To allow the sail to fold vertically, I replaced the spine of
the diamond kite with a double spine which I used as a hinge for the
kite in the manner shown in the messenger body diagram, above.

The diagram above shows the shape and dimensions of the first sail I used on
the lifting messenger and this works extremely well. The sail folds on some
hindges made from carbon fiber tubing. The sail release lines are attached
not near the bottom of the sail, but to either side to the cross spars to
hold the sail open.

No other lines are attached to the sail. Especially note to the lower part
of the spine. This allows the sail to flex along the plastic tubing holding
the hinges tubes, and lets the sial set its own angle to the wind.

Think of the sail as a diamond kite which has no bridle, the line being
attached directly to the cross piece, and you get the idea of the sail
setting its own angle.

As this sail is shaped like a proper kite it will actually lift the
messenger and payload up the kite line. It is so good it has lifted
'Tuffy' my para-koala, straight up a vertical line I held tight from a
ground peg. The load rose slowly but with a good wind it will do this.
I have had it climb up a very tight line angled at 75 degrees attached to a
34 cell tetrahedral kite (design courtesy of TetraLite Kites). It also
climbs my 1.5 genki kite with my parafauna! A
situation which I can guarantee a older drag style ferry will not do, when
It also has no problems with lesser sloping lines like my UFO rotor kites,
though with the lower angled lines it behaves more like a normal 'drag'
style messenger, with some extra lift.

UPDATE, 12th May 1998 :- I just finished my latest messenger
using a diamond sail as my messenger sail.

The larger sail (tyvek, with a dragon motif painted on) is 1 meter long
and 1 meter accross, to allow Tuffy to ascend in very light winds. The
cross piece for the diamond has been moved downward so it is 1/4 the
distance from the top (25cm) instead of the 1/5 measurement (used
above). This change of the cross piece position was the the result of
further undocumented experiments, and lets the wind set the messenger
sail angle better.

Also I added two small holes at the very top of the sail so I can tie a
short pice of string, or clip, across the kite line gap in the sail, after
it has been attached to the kite line. This reduces the bend in the
longerons due to the need for this gap, especially when the sail is full of
wind.

The new body of the messenger is also 90cm long with the load support
'hook', 20cm in front of the lower line support post. In my experimental
messengers before this, with the hook so close to the lower end of the
messenger, the load weight and sail lift caused the front of the messager to
lift the front load support from the kite line. So in the new one I extended
the release rod to move the load away from the line line support at the
lower end of the messenger body.

Also I added a set of lines between the sail and a large rubber o-ring (I
happened to have handy) which I throw over the front line support piller to
prevent 'sail flop' in turbulence, or when behind a wind shield at ground
level.

Sail Flap

One final point before you go and try your own experiments, I used thin
garbage bag plastic for my prototype sails above, and have found that the wind
flaps the trailing edge of the sail so much that often the messenger comes
down extremely slowly.

To stop this flapping I have taped some pieces of BBQ skewers I had
handy on the kite field to the sail. This is a bit like the battens used
in sails such as those in sail boats, windsurfers, and hang gliders.
After adding them the sail will no longer flap when released, allowing
the messenger to descend more quickly.

Also I found that adding a link across the very top of the sails, stops the
two spines bending back with the wind, and stops the lower part of the sail
from becomming too loose. But make that link detachable so you can remove the
kite line from the slot in the sail, so just a bit of telephone wire, hook, or
clip will do.

When I later upgraded to a larger sail made with Tyvek the BBQ 'battens' were
not needed, allowing the sail to roll up easily. But the link at the top
(stop spine bending) is still nessary. As such to release teh messenger from
the line I have two attachment hangers (stainless steeel cotter pins) and
a clip at the tp of the sail.

According to Graeme, his messenger's sail dimensions are approx. 1.5
metres across the top and the vertical spar is cut at 70cm. The spars
are 5.5 mm carbon fibre.

This looked interesting. First the sail is hinged horizontally instead of
vertically and was released by a single line attached to the spine. The
sail as such does not fold in half as the other sails. Instead the sail
remains open as the messenger descends, which in turn slows the descent
somewhat and may require a heavier messenger body to descend in high winds
and lower angled kite lines.

The following is a diagram of my version to attach to the messenger
above. I however only used 3mm fiberglass spars (as I did in the other
sails and I sized the sail so that the sail area will work out to the
same as the diamond messenger above (this is an experiment remember).

This sail worked, and flew up the kite line well. Unfortunately it could
not lift Tuffy. This was probably due to my use of 3mm fibreglass for
the cross spar, which as it did not have any sail support in front of it
was bent very heavy backward by the wind. This in turn loosened the
sail, destroying any lifting ability the sail may have had in my first
trial.

I replaced the leading spar with carbon fibre tube and while the sail now
lifts it did not seem to lift vertically as well as a diamond sail of the
same size (which was smaller for storage as the diamond folds in half). For
low angles of kite line the sail has no problem but for higher angles it
seems to be very particular about the length of the release line to set the
angle of sail into the wind.

Also I don't think a plastic sail worked well due to the way plastic
streaches. Ripstop verions of this sail would probably do better.

With the success of the diamond sail above I decided I will next try a
really high angled kite sail which should give even better lift.
The following sail is basically a genki kite sail (see this traditional genki kite plan), but without the center section.

This sail did not work!

When I tried this sail I found that the sail tends be unstable, wanting
to spin and twist around the kite line. The problem I think is that the
lift provided by the sail is just too great. As such it wants to not
only climb the kite line but raise the kite line higher! As it can't do
this and remain stable (center of forces is behind and below the kite
line) it will instead spin around and around and around the kite line.

I still figure this sail will work and will provide even better lift
than the diamond kite, but may require a stabilizing keel, such as
provided by the bridle keels of a real genki kite, perhaps a keel
like those used in roller kites (See this Pearson-Roller
Plan).

Maybe if the genki sail was repositioned so that the center of forces is
above the kite line the messenger will not only lift the payload, but
perhaps support the kite line itself! Of course the line connections
between the messenger and the kite line may also require some revision
to handle the messenger lifting the kite line itself!.

Basically I have come to the conclusion that while some sail lift is
good, too much is bad. It is only becuase of this conclusion that the
genki sail is still shown in this plan.

Sail Design

Guy Reynolds had some thoughts on messenger sail design, after his own
messenger experiments....
I have been considering at your Genki sail failure, and come up with a
theory that may explain why your Genki sail (in the published design) fails,
the diamond works and how many other sail forms, including the Genki could
be made to work whilst others couldn't.
I believe that your theory about the sail trying to lift the line as well as
itself is partially correct, but necessarily because of lifting power of the
kite. My theory is that the problem is to do with the natural angle of
elevation of the sail compared with the lifting/pilot kite and the position
of the line/messenger body in relation to the sail. One only has to look at
man lifting kites where the lower kites run freely up the kite line before
hitting conical stops, these kites have a huge amount of lift but remain
relatively stable when running up the line. This set me thinking and gave me
a clue to the possible causes of the sail instability problem, rather than
taking messenger in isolation, consider it as a lower kite in a train, the
body of the messenger as the kite line, and assume that the angle of
elevation of the line is the same or more than that naturally reached by the
design of the kite being used.
Take the diamond; if we extrapolate the kite line beyond the bridle point
and through the kite, it roughly passes through the kite at the crossing
point of the spars, which is where we bridle from for a train and where the
hinges are in the messenger, hence the sail is stable
Now consider the Genki; I don't own a Genki so have no first hand
experience, and can find no reference to a Genki train, but looking at
photographs and plans and extrapolating the kite line up into the kite, it
appears to pass through the sail well below the horizontal spar. Thus what
you have with your Genki messenger sail is effectively an incorrectly
bridled and thus unstable Genki. What I believe is happening is that the
sail is trying to change its angle of attack (lifting the line as you
describe it) to reach a stable point i.e. with the line/messenger body
passing through the sail below the horizontal spar, but because the
line/messenger body position is fixed it is flipping over the line where
lift is lost, dropping back and going into a spin around the line. If the
theory is correct it should be possible to make the Genki sail work,
particularly with your messenger design, by positioning the horizontal spars
higher up above the messenger body, so that the line/messenger body passes
through the sail where the effective line would be for a properly bridled
Genki.
However, following the same thought process, the same problem could occur
but possibly to a lesser degree even with the line/messenger body passing
through the correct point in the Genki sail if the angle of elevation of the
line is less than that normally achieved by a Genki. This is because the
sail will still try and lift the line, however this time it is only
constrained by the lifting/pilot kite holding the line, and not by its own
construction so the instability could/should be less.
I would thus like to postulate three basic rules for messenger sail design,
if using a kite design as the basis of the sail.

In its kite form the sail must be inherently stable i.e. must not require
a tail for stability.

The line/messenger body must pass through the sail at the point where the
extrapolated line would effectively pass through the sail of a correctly
bridled kite of the same design.

The natural angle of elevation for the kite on which the sail is based
must be less than the natural angle of elevation of the pilot/lifting kite
being used.

If my theory is correct the a Delta Conyne Kite should work as the effective
line runs through the gap in the middle of the kite, which is where the line
for a train is run, and it should just be a case of designing sail such that
the horizontal spreader spar is positioned just where there effective kite
line passes through the back of the sail. However, it will only work
effectively so long as I use a Delta Conyne as a lifting/pilot kite or a kite
that has similar or even greater natural angle of elevation.
As yet this is only a theory, I have yet to prove it in practice
Regards
Guy

Future Things To Try

These are ideas and thoughts which I may or may not experiment further
with... You are welcome to try them out, and I'd happy to include or
reference your own results.

Rokkaku sail.
(Suggestion from Carlos Simoes )

Trial a folding delta lifting sail.
This would probably have to also be almost on top of the kite line.

Two sails on the messenger body to provide greater lift.
This was seen in a number of messenger photos, but these have since
disappeared from the net.

Highly Experimental (untried) :-
Put the sail on the top of the ferry with the parafaunas weight
holding the sail above the kite line. When bear drops the weight
change will spin the ferry 180 degrees and release the sail (to
fold up) and it comes back down again!

The sail should be a high lift sail such as a genki style sail (see
above) or perhaps a delta sail. Weight would also be critical I think
for varing winds.

For more information about peoples experience with building this
messenger (or others) and what results they have achieved I suggest you
look at the various Responses I have
recieved. Many thanks to all who have replied.
If like this plan, and/or build one, please mail and let me know what you
think. Including any ideas, suggestions or other experiences. That way I can
add them to the above so others can read and benifit from your results. :-)
Photos especially welcome!